The conversion of water gas is carried out in industry mainly by using oxidic heterogeneous catalysts, which, however, are only effective at relatively high temperatures of, for example, 200.degree. to 500.degree. C.
Furthermore, catalysts are known which catalyse the reaction in a homogeneous phase, for example soluble rhodium compounds such as Rh.sub.6 (CO).sub.16. However, these homogeneous catalysts have the disadvantage that they are difficult to separate off, thus requiring subsequent work-up procedures.